<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: 麦当苗儿 <zuojiazi@vip.qq.com> <http://www.zjzit.cn>
// +----------------------------------------------------------------------

namespace OT;
use Think\Db;

//数据导出模型
class Database {
	/**
	 * 文件指针
	 * @var resource
	 */
	private $fp;

	/**
	 * 备份文件信息 part - 卷号，name - 文件名
	 * @var array
	 */
	private $file;

	/**
	 * 当前打开文件大小
	 * @var integer
	 */
	private $size = 0;

	/**
	 * 备份配置
	 * @var integer
	 */
	private $config;

	/**
	 * 数据库备份构造方法
	 * @param array  $file   备份或还原的文件信息
	 * @param array  $config 备份配置信息
	 * @param string $type   执行类型，export - 备份数据， import - 还原数据
	 */
	public function __construct($file, $config, $type = 'export') {
		$this->file = $file;
		$this->config = $config;
	}

	/**
	 * 打开一个卷，用于写入数据
	 * @param  integer $size 写入数据的大小
	 */
	private function open($size) {
		if ($this->fp) {
			$this->size += $size;
			if ($this->size > $this->config['part']) {
				$this->config['compress'] ? @gzclose($this->fp) : @fclose($this->fp);
				$this->fp = null;
				$this->file['part']++;
				session('backup_file', $this->file);
				$this->create();
			}
		} else {
			$backuppath = $this->config['path'];
			$filename = "{$backuppath}{$this->file['name']}-{$this->file['part']}.sql";
			if ($this->config['compress']) {
				$filename = "{$filename}.gz";
				$this->fp = @gzopen($filename, "a{$this->config['level']}");
			} else {
				$this->fp = @fopen($filename, 'a');
			}
			$this->size = filesize($filename) + $size;
		}
	}

	/**
	 * 写入初始数据
	 * @return boolean true - 写入成功，false - 写入失败
	 */
	public function create() {
		$sql = "-- -----------------------------\n";
		$sql .= "-- Think MySQL Data Transfer \n";
		$sql .= "-- \n";
		$sql .= "-- Host     : " . C('DB_HOST') . "\n";
		$sql .= "-- Port     : " . C('DB_PORT') . "\n";
		$sql .= "-- Database : " . C('DB_NAME') . "\n";
		$sql .= "-- \n";
		$sql .= "-- Part : #{$this->file['part']}\n";
		$sql .= "-- Date : " . date("Y-m-d H:i:s") . "\n";
		$sql .= "-- -----------------------------\n\n";
		$sql .= "SET FOREIGN_KEY_CHECKS = 0;\n\n";
		return $this->write($sql);
	}

	/**
	 * 写入SQL语句
	 * @param  string $sql 要写入的SQL语句
	 * @return boolean     true - 写入成功，false - 写入失败！
	 */
	private function write($sql) {
		$size = strlen($sql);

		//由于压缩原因，无法计算出压缩后的长度，这里假设压缩率为50%，
		//一般情况压缩率都会高于50%；
		$size = $this->config['compress'] ? $size / 2 : $size;

		$this->open($size);
		return $this->config['compress'] ? @gzwrite($this->fp, $sql) : @fwrite($this->fp, $sql);
	}

	/**
	 * 备份表结构
	 * @param  string  $table 表名
	 * @param  integer $start 起始行数
	 * @return boolean        false - 备份失败
	 */
	public function backup($table, $start) {
		//创建DB对象
		$db = Db::getInstance();

		//备份表结构
		if (0 == $start) {
			$result = $db->query("SHOW CREATE TABLE `{$table}`");
			$sql = "\n";
			$sql .= "-- -----------------------------\n";
			$sql .= "-- Table structure for `{$table}`\n";
			$sql .= "-- -----------------------------\n";
			$sql .= "DROP TABLE IF EXISTS `{$table}`;\n";
			$sql .= trim(isset($result[0]['create table']) ? $result[0]['create table'] : $result[0]['Create Table']) . ";\n\n";
			if (false === $this->write($sql)) {
				return false;
			}
		}

		//数据总数
		$result = $db->query("SELECT COUNT(*) AS count FROM `{$table}`");
		$count = $result['0']['count'];

		//备份表数据
		if ($count) {
			//写入数据注释
			if (0 == $start) {
				$sql = "-- -----------------------------\n";
				$sql .= "-- Records of `{$table}`\n";
				$sql .= "-- -----------------------------\n";
				$this->write($sql);
			}

			//备份数据记录
			$result = $db->query("SELECT * FROM `{$table}` LIMIT {$start}, 1000");
			foreach ($result as $row) {
				$row = array_map('addslashes', $row);
				$sql = "INSERT INTO `{$table}` VALUES ('" . str_replace(array("\r", "\n"), array('\r', '\n'), implode("', '", $row)) . "');\n";
				if (false === $this->write($sql)) {
					return false;
				}
			}

			//还有更多数据
			if ($count > $start + 1000) {
				return array($start + 1000, $count);
			}
		}

		//备份下一表
		return 0;
	}

	public function import($start) {
		//还原数据
		$db = Db::getInstance();

		if ($this->config['compress']) {
			$gz = gzopen($this->file[1], 'r');
			$size = 0;
		} else {
			$size = filesize($this->file[1]);
			$gz = fopen($this->file[1], 'r');
		}

		$sql = '';
		if ($start) {
			$this->config['compress'] ? gzseek($gz, $start) : fseek($gz, $start);
		}

		for ($i = 0; $i < 1000; $i++) {
			$sql .= $this->config['compress'] ? gzgets($gz) : fgets($gz);
			if (preg_match('/.*;$/', trim($sql))) {
				if (false !== $db->execute($sql)) {
					$start += strlen($sql);
				} else {
					return false;
				}
				$sql = '';
			} elseif ($this->config['compress'] ? gzeof($gz) : feof($gz)) {
				return 0;
			}
		}

		return array($start, $size);
	}

	/**
	 * 析构方法，用于关闭文件资源
	 */
	public function __destruct() {
		$this->config['compress'] ? @gzclose($this->fp) : @fclose($this->fp);
	}
}
